Pawl-and-ratchet power appliance



M ay 8, 1923.

P. MacKENzlE PAWL AND RATCHET POWER APPLIANCE Filed May 17. 1922 2 Sheets-Sheet l @www tormgs {Ilili Cf; y

May s, 1923.

. ,454,398 P. MacKENziE P IAWL AND RATCHET POWER APPLINCE Filed May 1v. 1922 2 sheets-sheet 2 Patented May 8, 1923.

- 1,454,395 y,fr replce.,

rAwL-ANn-RATCHET POWER APPLIANCE.

Application filed May. 17,

rBe" itkn'own that I, PHILIP MAoKnNZIma citizen' oii Qanada,,residing at the city. and county of San `Francisco and State of California,`ha'-ve invented new and usefullmprvements in-Pawl-andRatchet Power Apl' pliances, or which the following isfafspeci.-

cation.

"This-invention relates to pawl and ratchet power appliances, especially intended for use in connectionfwith jacks, capstans Tand the'like. The object of the invention is to simplify andimprovethe construction and operation' of yai mechanism of this sort.

`In thetypetdeViCe under consideration there is a'rocking pawl lever which actuates l a'pair lof pav'lsi'for driving av ratchet wheel,

the wheel beingfadvanced one or'more teeth on eachforward vmovement of therlever and a similar distance Yon the backwardmovementf the lever. yThe present improve- 5- ments contemplate thejp-rovision` of mechalever. f

'y One form which myinvention may' assume is 'exemplified in the following description and Aillnstratedlin the accompanying"drawings,jn which-- igpl 'shows a side elevation, partly in section, -of mechanism embodying my in- 'vention 40 Fig.l 2 shows a detaily view in side elevation ofthe pawl mechanism in position for drivthe; ratchet wheel inl a reverse direction Jfrom that shownv iny Fig. l.

' Fig. 8 shows a detail of a novel form of spring employed'for placing tension upon thev pawls.

Figfi shows` adetail vsectional view of the 'cor'inections'lo'etwei-znI the'` pawls and lever.

y Figs. '5,6 and "7 show different views of the pawl mechanism in posi-tion for releasin the ratchet wheel, lone tooth ata time.

igfB shows aview 'of the pavvl mechanisrn entirely disengagedjfrom'the ratchet wheel.

ReferringI in detail to the accompanying drawingl have shown a ramelO' having a ratchet wheel A1l journaled thereon, said ratchet wheel actingy to operateaglifti-ng or hoisting, device. -As .here f illustrated, the ratchet wheel is mounted .y tipo-1 1 a` .s hatt which carries a capstan/V 14,-, the latterheing fitted .with the usual windingrogpe l5. APivoted on the frame to yonefsideo'f the ratchet wheel is apawl' lever; 16 to either side yofthe axislof which is connected a'pavvl 17 Q co-operating with'v theqteeth 'on the yratchet wheel.'

Connected .to each pawlt isn-.a spring wire i ,18

iixed' toa post 19. Around each postaisZ--a coiled spring 20, the ends yof'vvhichf,stagadtille the Wire andare held againstfiuIlW-inl'difng movement by .a lug 2l, Thusethe seeing wir@ may -be niitunde'ritensonin either direction wit-hout; unwinding the- .coil.

Both postslaare fixed npQnfaCplate/ZQ' l which l. pivots iabout an f axis?y y23 fand is 'cQntrolled! by means l of a handle org-garra; Fenster lugs/. 25 fastenedrto the iranienne arranged at oppositeends of theyvmovement ofthef arm Q eyand, serve toretaingthelatter gin adjusted j position. lie-the arm )Joe moved to the, positionY shown in" 51,-;fthe spring Wires are under tension togholdthe parvls inaengagement vwith the ratchetfteeth, y

and ,therefore when the paWlf le'ver is rocked theiratchet Wheel is -fed orwardlyzonefor more teeth to each stroke. `Vhen the-aren 24 is in: the. position shown iin "Fig. 2, g fthe tensiomon` the springf wiresitendsgto. force the pawls out oi' engagement withthejratchet teeth.Av @n "f The inner pawl has a cam ssuraceffvto loo-operate :with a lcam surface -27 Qin-fthe outer pawl. Likewise, theyontergpawl hasfza cam surface 28130l coi-operate v vfithi alfp'ivoted cam member 29. This cammemberf-29-is held- `inwardly yhy a spring-30@ and aisetgscrev 311:is provided. for regurlating.. the tension'rof the: spring. Also-a; seti screw -82 is'arranged at thefother end-.ot the pivoted tam-towassst in regulating the@ position ofthe-said. pivvoted cam. JA latch deviceie fi's provided tor permanently f holding the said pivo-ted .cam

ont 'of contact `with; thel .outer pajwl member.

To enaihfle the'fdeviccftohe operatedin-a reverse direction, one tooth at a.-`-'m6,f;the tension f on i the springsv on' thel p-awls .i isf"re- 'versed,1fas shown-infEigJQ; It theglever tbe in 'rearward position,l aszshownJin-fsaidlig.

'2, the onter pawl will heotof; engagement with its tooth,l `butits position-.will he such -asito1 retain the inner -pa'wli in engagement a withl the ratchet-'wheel'aso 'las .tog 1'efstraingthe load. As the lever starts to move forwardly, as shown in Fig. 5, the outer pawl will be advanced and the inner pawl will recede. As the outer pawl comes forwardly, it will be moved into engagement with a tooth of the ratchet wheel by the action of the pivoted cam 29, and at the same time the inner pawl, resisting the load, will remain engaged with the ratchet wheel. When the lever reaches its forward position, as shown in Fig. 6,' the outer pawl has fully engaged a ratchet tooth and taken up the load, leaving the inner p-awl free to move out of engagement with the ratchet wheel under the influence of its spring. As the lever starts to move rearwardly, as shown in Fig. 7 the outer pawl is receding while resisting the load, and the inner pawl is advancing free of the ratchet teeth. As the two pawls approach their cooperating cam surfaces contact and force the inner pawl into engagement with a ratchet tooth. Just before the lever reaches its extreme rearward position, shown in Fig. 2, the. inner pawl has taken up the load, leaving the o-uter pawl free tomove out of engagement with the ratchet wheel.

If the pivoted cam 29 be held by the latch device 33 out of engagement with the cam surface on the outer pawl, then the action of the sprin wires 1S will be to lift both pawls out of engagement with the ratchet teethand allow the said ratchet wheel tobe turned freely in either direction, as shown in Fig. 8.

The above described construction permits the change from forward drive to reverse drive to be made even when the ratchet wheel is under full load, since it is only necessary to move the arm or handle 24 from one position to the other and to set the pivoted cam 29 accordingly.

Another improvement embodied in the present structure is the provision of novel means for taking up the thrusts imposed upon the bearings of the pawl lever. This Ais in the form of a segmental late 34, pivoted at 35 and co-acting at its orward position with a semi-circular plate 36, the latter being fixed upon the axis of the pawl lever. The rear or pivoted end of the segmental pawl 34 abuts against a thrust member 37 removably litted into the corner of the frame. Thus the thrusts on the bearings of the pawl lever are transmitted to the corner of the frame and the parts exposed to the greatest wear are removable and replaceable.

The manner in which I attach the pawls to the pawl lever is also advantageous. The pawl lever has a stub shaft or boss 38 which has a segmental portion 39 cut out of its front. Longitudinal recesses 40 are formed in the boss at each end of the cutaway portion and into these recesses the pins 41, forming the pivots of the pawls, are iniaasas Serted. Then a. filling strip 42 is placed between the protruding pawls and one end of the cutaway segmental portion and said strip is fastened in place by means of screws 43 inserted through one end of the boss. One end of the boss or stub shaft is squared, as shown at 44, to receive the pawl lever.

Various changes in the construction and arrangement of the several parts herein shown and described may be employed without departing from the spirit of the invention as disclosed in the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

l In a pawl and ratchet power appliance, a frame, a ratchet wheel journaled thereon, a pawl lever mounted for rocking movement on the frame, a pawl pivoted to the pawl lever on either side of the axis thereof and cooperating with the teeth -on the ratchet wheel, means for retaining the pawls yieldingly in engagement with the teeth of the ratchet wheel for driving the wheel forwardly and means for optionally causing alternate disengagement and reengagement of the pawls to permit the ratchet wheel to be reversed when under load, said last mentioned means comprising yielding means to exert an outward pressure on each of said pawls, cio-acting cam surfaces between the two pawls to control the outward movement of the inner pawl, a cam surface on the outer pawl and a co-acting adjustable cam to co-operate therewith for the purpose of controlling the outward movement of the outer pawl.

2. ln a pawl and ratchet power appliance of the character described, a ratchet wheel, a pawl lever, a pair of pawls thereon for actuating the ratchet wheel and spring means for exerting pressure on the pawls optionally in opposite directions comprising a spring wire for each pawl, a post to which the wire is fixed, a coil surrounding the post and having its ends engaging at opposite sides of the wire and means to hold one of the ends stationary when the other end is acted upon by the wire.

3. ln a pawl, and ratchet power appliance of the character described, a ratchet wheel, a pawl lever, a pair of pawls thereon for actuating the ratchet wheel and spring means for exerting pressure on the vpawls optionally in opposite directions comprising a spring wire for each pawl, a post to which the wire is fixed, a coil surrounding the post and having its ends engaging at opposite sides of the wire, means to hold one of the ends stationary when the other end is acted upon by the wire and means to swing the posts in unison to reverse the direction of the tension applied by the wires upon the pawls.

4. In a pawl and ratchet power appliance,

a frame, a ratchet wheel journaled thereon, a pawl lever mounted for rocking movement on the frame, a pawl pivoted to the pawl lever on either side of the axis thereof to co-operate with the teeth on the ratchet wheel, means for yieldingly retaining the pawls in enga ement with the teeth of the ratchet wheel or driving the wheel forwardly and means for causing the pawls to disengage and re-engage alternately with the ratchet wheel for reversing the latter under load, said reversing mechanism comprising yielding means tending to force the pawls out of engagement with the teeth of the ratchet wheel, a cam co-operating with the outer pawl to cause the latter to engage a tooth near the termination of its advancement and co-operating cam surfaces between the inner and outer pawls to cause the inner pawl to engage a ratchet tooth near the termination of its advance stroke, said cam surfaces being out of contact on the receding stroke of each pawl, said first-mentioned cam mechanism being movable t0 entirely clear the outer pawl whereby to permit both pawls to move permanently out of engagement with the ratchet wheel.

5. In a device of the character described, a ratchet wheel, a rocking pawl lever, a pawl pivoted to said lever at each side of the axis thereof for actuating the ratchet wheel, said lever having a boss provided with a cutaway portion to receive the pawls, pins on each side of said pawls fitting in recesses at the ends of the cutaway portion and a removable filling strip between the pawls and one end of the cutaway portion to retain the pawls in place.

PHILIP MAOKENZIE. 

